Diamondbacks Batting – Do Pitch Types Matter?

A creative approach will provide new insights.

Instead of looking at each season’s batting, let’s look at 13 position players who are likely to account for the majority of Diamondbacks’ at-bats in 2021. These 13 position players were the same as Roster Resource projected on 1 March, except for my addition of Daulton Varsho. Including Varsho was bold, although his assumed pitches seen as a batter are less than 8 position players. An additional assumption is that outfielders Kole Calhoun and Tim Locastro will be back at 100% by the end of April. The position players are:

• Christian Walker
• Kole Calhoun
• Ketel Marte
• David Peralta
• Eduardo Escobar
• Carson Kelly
• Nick Ahmed
• Tim Locastro
• Daulton Varsho
• Stephen Vogt
• Asdrubal Cabrera
• Josh VanMeter
• Andrew Young

For these 13 position players, let’s look at three questions:

• Over the last 7 seasons, did they see changes in the types of pitches (fastballs, breaking pitches, offspeed pitches) they received in the Majors?
• Last season, for each type of pitch, were their wOBAs better than last season’s Diamondbacks?
• Last season, for each type of pitch, were their wOBAs improved or worsened compared to 2019?

Over the last 7 seasons, did they see changes in the types of pitches they received in the Majors?

Before proceeding, let’s look at the specific pitches that are grouped into fastballs, breaking pitches, and offspeed pitches. They are shown in the following table.

Now that we have grouped the pitches, for our anticipated roster of position players, let’s look at whether the percentage of each type of pitch changed over the last 7 years.

Data from Brooks Baseball.

Fastballs remain important. Although the most common pitch type remained fastballs, the percentage of fastballs fell from 64.5% to 57.7%. What replaced those fastballs?

80% of the former fastballs were replaced by breaking pitches, while 20% were replaced by offspeed pitches. That resulted in breaking pitches increasing to 27.3% of pitches received, and offspeed pitches increasing to 15.0% of pitches received.

How do they compare to the 2020 Diamondbacks’ team?

For each of the 3 types of pitches, this season’s anticipated roster of position player had a better pitch-weighted average wOBA than the 2020 Diamondbacks. Likely, the team’s wOBA will improve this season. The improvement will be dampened due to lack of the designated hitter position in the NL.

• Against fastballs, the team wOBA was .316, ranking 29^th of the 30 teams in the Majors. The anticipated roster of position players had an average wOBA of .332. Because of the universal designated hitter in 2020, this comparison to other teams was fair.
• Against breaking balls, the team wOBA was .297, ranking 6^th of the 30 teams in the Majors. The anticipated roster of position players had an average wOBA of .326, which, if they had been a team, would have been the best team in the Majors.
• Against offspeed pitches, the team wOBA was .255, ranking 25^th of the 30 teams in the Majors. The anticipated roster of position players had an average wOBA of .281.

Last season, for each type of pitch, were their wOBAs improved or worsened?

Before we discuss the comparison of 2020 to 2019, let’s look at a table of the position players. The 2020 wOBAs are shaded green if they improved by at least 10% better, and they were shaded red if they worsened by at least 10% worse.

Data from Baseball Savant.

Against fastballs, 7 of the 13 position players had significantly worse wOBAs. Only Tim Locastro had a significantly improved wOBA.

This disappointment is not news to the Diamondbacks. This season they added a round of batting practice with a hitting position that makes batter reaction time closer to in-game fastballs.

“For one round during BP, Arizona’s hitters step up to the new mat, where they have to react more quickly to get their barrel on the incoming pitch. ‘Now a 70 mile-an-hour batting practice is 90 miles an hour,..’ Coles said.” Zach Buchanan Athletic article.

Against Breaking balls, the anticipated roster was outstanding. Nevertheless, they could be better when Escobar, Marte, and Peralta regain their 2019 levels of batting.

Against offspeed pitches, Asdrubal Cabrera was consistently great (wOBA of .383 in 2019 and .412 in 2020). The most improved were Tim Locastro and Nick Ahmed. And it will be great when Kelly and Vogt regain their 2019 levels of batting.

Pitch type matters.

Despite the dropping percentage of fastballs, they are the majority of pitches seen by the Diamondbacks’ roster. Last season, for most of the roster, their results against fastballs worsened. There are several reasons (better roster, better practice methods, and longer season) to predict the Diamondbacks will improve against fastballs.

The Diamondbacks batters are outstanding against breaking pitches, which they are seeing more frequently. If the roster had been a team last season, they would have ranked number one in wOBA against breaking pitches.

Asdrubal Cabrera had the Diamondbacks’ best wOBA against offspeed pitches. The team has potential for improvement against offspeed pitches.